Answer :

Solution :

The average success rates of these four schools will be

$\Rightarrow \frac{\left\{\left(\frac{280}{500}\right)+\left(\frac{330}{600}\right)+\left(\frac{455}{700}\right)+\left(\frac{240}{400}\right)\right\}}{4}\times 100=\frac{0.56+0.55+0.65+0.6}{4}\times 100=59\mathrm{\%}$

∴ The average success rates of these four schools = 59.0%